New wake turbulence departure separation
 

So as of February 2014 we'll need to provide 4 miles between two Heavy departures (in line with the rest of Europe). I've personally never had a wake turbulence report from a heavy follwing a heavy 'wheels-up'. This is obviously going to affect one or two airfields a lot more than any others in this country.

Thoughts?

I don't remember any H vs H wake turbulence reports either, but that pairing isn't as common for me as my more usual suspects - minibuses close together and of course old faithful 757s. The crash on Queens, NY 2001 proves that it can happen, but 4 nm does seem rather OTT in light of the apparent lack of evidence requiring it.

This has previously been discussed in the Heathrow thread in Airlines & Routes because that is where it is most likely to have an impact.

The CAA claims to have reports of encounters which suggest the current separation is insufficient. They are proposing the ICAO standards as an alternative but have left the door open for Airports to adopt alternative standards on a local basis if they can provide a safety case because there is apparently no scientific evidence to support the ICAO standards.

Quick link: http://www.pprune.org/airlines-airpo...ml#post8034606 et seq

Ahh, apologies

Why 4nm on heavies when everything else is time based?

Also, how is anyone expected to get 4nm - when do you give TO clearance. More likely going to be 4.5/5/5.5 or less if the second heavy is spritely and the first fully loaded.

Stupid stupid stupid.

The why is surely to guarantee radar has std vortex wake separation on handover from the tower. It's obviously only between heavies as a 2,3 or 4 minute vortex wake spacing provides much greater in line spacing.
Achieving it is not exactly rocket science, either use rwy length or RSVA until you have 4 miles.

We can't use RSVA to reduce wake turbulence separation though.

The instruction from the UK CAA specifically states that the 4nm must exist at the point the follower gets airborne, not when it paints on radar or on handover.

It will be interesting to see what sort of 'alternative means of compliance' is devised.

Interestingly, in the ICAO docs, the 4nm requirement is part of the surveillance chapter, referring to departures following the same initial track.

Maybe I could comply by turning my tower radar screen off, thus negating the requirement for the 4nm?:}

If tower controller does not have a serviceable ATM, how can you provide 4m??

Europe Pah!
 

What about combining the other future change .

"Behind the departing after it's passed four miles clear take off behind ":ugh:

<<Behind the departing >>

Where did you get that phrase? Or is it a recent reversion to long ago?

120 secs is the same as 4 nm give or take the odd yard or two.

HD,
http://www.caa.co.uk/docs/33/CAP493S...tion201303.pdf

It all depends, 120 seconds rotation-rotation gives us about 7-8 track miles when the follower paints on the ATM.

Apologies all round. It did change to "After the departing" many years ago after a light aircraft told "Behind..." did just that and got blown around a bit!

I really don't like the new Rwy conditional phraseology!

ICAO phraseology again, " behind the landing line up behind" . Used it in Dubai, the AFTER the landing etc phraseology I used at Gatwick was definitely better!!

However that is progress????

Yes, I'm very surprised that they reverted to the old and potentially dangerous phraseology.

Not sure which planet 120 seconds gives you four miles on between heavies. How we acheive four miles is by launching them rwy length apart. That's roughly 4000m but the temperature has an effect on that. You also have to take A/C types and performance into account but that's our job.
Gonzo, I think you'll find that they will have to further refine the 4 mile requirement because it s as unrealistic in your environment as it is in ours.

"Behind the departing..."

Yes, heaven forbid we use ICAO standard phraseology that doesn't require pilots to learn different phraseology for different countries. No chance at all that the current nonsense could lead to misunderstandings :rolleyes: